The pulping of wood by the polysulfide process has attracted much attention in the industry over the last few years due to a higher yield of pulp from wood than obtainable by the Kraft or other conventionally used pulping processes. The increasing cost of wood, which is the major cost in pulping, has forced the industry to thoroughly evaluate any alternative which promises a higher yield. Such a benefit is not without some drawback and in this instance it takes the form of increased requirements of sulfur to form the sodium polysulfide compound usually designated as Na.sub.2 S.sub.x in the cooking liquor. The effects of the additional sulfur requirements do not show up merely in increased sulfur costs, but are manifested in the form of increased corrosion problems, smelt conditions with increased potential for explosions, and a number of costly pollution problems. Such side effects, coupled with the absence of an inexpensive recovery system for the sulfur have been inhibiting factors in the acceptance of the polysulfide pulping process as a viable alternative to conventional systems now employed.